Performance Evaluation of an Air Cooled Diesel Engine Fuelled with Neat Neem Oil and Diesel Blends

Abstract

An experimental study has been carried out to investigate the performance of a single cylinder air cooled diesel engine fuelled with neem oil-diesel blend (5%, 10%, 15% and 20% by volume) and the results are compared with baseline data of diesel. Brake thermal efficiency of the engine with 5% neem oil blend was found to be marginally higher than neat diesel operation at all loads indicating better combustion due to dissolved oxygen. However, with further increase in percentage of neem oil, brake thermal efficiency of the engine reduced significantly at higher loads possibly due to increased viscosity of the fuel impinging proper combustion. Brake specific energy consumption happen to be the lowest for 5% neem oil blend at all loads, however with subsequent increase in percentage of neem oil, full load brake specific energy consumption became lower at part loads and higher at full loads as compared to neat diesel operation. Smoke opacity of 5% blend was comparable to baseline data of diesel, but it increased substantially at higher blends. With increase in percentage of neem oil in the test fuel sample the exhaust temperature showed a downward turn reflecting a comparatively improved nitrogen oxides emission tendency and reduced thermal loads. Based on this experimental study, it is envisaged that in rural/agriculture sector of India where neem oil can be available at economical cost, 5% neem oil blend may be a good substitute for mineral diesel which in turn can save considerable amount of forex outflow for equivalent crude oil import.